Heat exchangers of the indirect plate pack type



' Oct 8, 1963 s. K.-JENSSEN ETAI. 3,106,242

' HEAT EXCHANGERS OF THE INDIRECT PLATE PACK TYPE Filed Feb. 27, 1961 5 52 N0 655 Jv am WmWW 5 v A 7 s 5a G This invention relates to heat exchangers of the indirect plate pack type in which plate-shaped heat transferring walls of thin plate material are arranged in packs with spaces between thev walls serving as passages for heat exchanging fluids.

The main object of the invention is to provide a heat exchanger with a high heat transfer-ring effect and great .power of withstanding pressure at the same time as the heat exchanger is suitable for use with a heat exchanging fluid containing solid impurities such as fibres, sludge, etc.

The invention is mainly characterized by the combination of each wall at each side being provided with a large number of dimples forming corresponding bosses on the opposite side of the wall pressed out from the plate material so that at each side of the wall such dimples and bosses are alternatively distributed over the wall side surface, the bosses of the one wall in every second interspace between adjacent walls being positioned in spaced registering relationship to the dimples of the other wall and in the remaining interspaces between adjacent walls being positioned in abutting registering relationship to United States Patent the bosses of the other 'walland at least to a great numher being welded together top against top.

The invention will now be described more in detail with reference to the accompanying drawing which diagrammatically and as an example illustrates an embodivment of a heat exchanger of the type to which the invention relate (FIGURES 1 to 3), as well as an embodiment of the invention applied to this heat exchanger (FIGS. 4to 10). In the drawing: -FIG. 1 illustrates a side view of a heat exchanger of the cross current plate type;

FIGS. 2 and 3 illustrate the same heat exchanger in section on the lines II'II and III-III in FIG. 1;

FIG. 4 shows a central section IV of FIG. lot a heat transferring wall of aheat exchanger'of the plate type on a larger scale;

FIG. 5 shows the same section as viewed in crosssection on the-line V-V in FIG. 4, said line being the vertical central line of the wall;

FIGS. 6 and 7 illustrate the same section as viewed in cross-section on lines VI-VI and VIIVII, respectively, in FIG. 4;

FIG. 8 illustrates the central section IV in FIG. 1 of another heat transferring wall of the plate heat exchanger on the same scale as FIG. 4;

FIG. 9 illustrates the same section as FIG. 8 taken on line IXIX in this figure, said line being the vertical central line of the wall, and

FIG. 10 shows the framed section X of FIG. 2 of the plate heat exchanger on the same scale as FIGS. 4 to 9.

Identical parts in the several figures are indicated with the same reference characters.

The heat exchanger 1 according to FIG. 1 consists of a pack of heat transferring walls 2 and 3 which are spaced by edge ribs 4. Every second space between the walls forms vertical passages 5 for one of the two heat exchanging fluids and the alternating spaces form horizontal passages '6 for the other fluid.

The walls which fior the sake of clearness are shown with smooth surface in FIGS. 1 to 3 are provided with 3,106,242 Patented Oct. 8, 1963 ICC pressings at least over the major portion of this surface. Walls 2 according to FIG. 4 and walls 3 according to FIG. 8 illustrate congruent sections IV of individual walls arranged in packs in registering positions, the registering centres of the corresponding surfaces of the walls being marked with The pressings consist of dimples 7 in both surfaces of the wall said dimples corresponding to boss-like pressings 8, likewise in both surfaces of the wall as most clearly shown in FIGS. 5 and 9 in which the neutral plane of the wall is indicated by a dash anddot line 9. In FIGS. 4 and 5 the bottoms of the dimples are indicated with small circles and the tops of the bosses with greater circles.

In the following descriptionthe surface a of the wall which in FIGURES 4 and 8 faces the viewer and which in FIGS. 5, 6, 7, 9 and 10 faces to the left will be referred to as the a-surface while the opposite surface b will be referred to as the b-surface. Walls which in the pack have their equally designated surfaces facing towards the same direction, for example to the right or to the left, respectively, according to FIG. 10 are called unidirected. Between unequally designate-d walls 2 and 3 respectively there is no diiference other than that one wall of the equally designated surfaces a or b has bosses at the places where the other wall has dimples and vice versa as will be clear by a comparison of FIGS. 4 and 5 with FIGS. 8 and 9. In the unequally designated surfaces, however, the dimples and bosses are located at the same places on both walls as viewed in the plane of the drawing. Thus, if two unequally designated unidirected walls 3 and 2 are assembled so as to cover each other entirely (FIG. 4 over FIG. 8 or vice versa) their unequally designated surfaces will face one another'and in these unequally designated surfaces the bosses of one surface will face the bosses of the other surface. If instead two equally designated walls 3 and 3 or 2 and 2 are assembled in the same manner (two FIGURES 4 or 8 being laid one over the other) the bosses of one of their unequally designated surfaces will face the dimples of the other surface.

According to the invention these different possibilities of distributing or assembling the walls in the pack are utilized in the following manner ,(see FIG. 10): Every second space 6 is formed between equally designated unidirected walls in which. thus the bosses of one of the unequally designated surfaces face the dimples or the other side, said spaces (free spaces) in all places forming free passage of a heat exchanging fluid in meandering paths between said bosses and dimples, Every sec ond free space is formed between one a-surface 2a and one b-surface 2b of two walls 2 while every second space is formed between one a-sunface 3a and one bsurface 3b of two walls 3. The remaining spaces 5 are formed between unequally unidireoted walls in which the unidirected bosses of the unequally designated surfacessaid bosses thus being oppositely directed-'engage the tops of each other at which they are welded together by means of spot-weldings 10, said spaces (sealed or jointed spaces) forming passages for a second heat exchanging fluid in meandering paths around the bosses. Every second seal-ed or jointed space is formed between one a-surface' 3a and one b-sur-face 2b of one wall 3 and one wall 2, and every second space is formed between one a-surface 2a and one b-surface 3b of one wall 2 and 3.

In this manner each of the jointed spaces will form a unit element which is capable of withstanding inner as Well as outer pressure and which is suitable for conduct ing a heat exchanging fluid under pressure, for instance steam as heating medium, and not containing materials which stick to portions forming bridges across the space. The free spaces 6 are adapted for conducting media containing such material, for example fibrous or sludgecontaining liquids. Pressure in said spaces 6 in an apparatus according to FIGS. 1 to 3 will be effectively taken up by the outermost elements 5 at the both free ends of the pack said elements functioning as a jointed double wall of substantial rigidity. Of course, this fact does not prevent that it is possible in known manner to fix the pack between particular supporting walls at these ends so as to obtain a greater strength against the bursting action of pressure in the spaces 6. With such supporting walls or when such spaces are approximately free of pressure also the outermost spaces of the pack may consist of free spaces. The meandering passages which both types of spaces form, highly contribute to the turbulence and thus to a high heat transferring effect.

From a comparison between FIGS. 5, 6 and 7 of which the two last mentioned ones. are cross-sections along the lines VI-VI and VII-VII of FIG. 4, respectively, it will be clear that the walls are vaulted or arched at all places except the small plane portions of the dimples and bosses. This shape results in a great rigidity of the wall and causes that the meandering bordering surfaces of the spaces throughout are 'free from corners or edges which could collect impurities.

The pattern according to which the pressings are distributed over the walls may be of any shape provided that the pattern is common for all walls. In the case illustrated in the drawing, however, this pattern has a special character resulting in particular advantages. A comparison between FIGS. 4 and 5 shows that if a wall according to FIG. 4 is turned 180 either in its plane around an axis transverse to the wall and passing through the centre of the wall or turned right about face around the central line V-V in the plane of the wall the appearance or image of the section IV will change from that shown in FIG. 4 to that shown in FIG. 8. This is due to the fact that (1) the distribution is such that on each surface of the Wall for each boss there may be found a dimple on a straight imagined line drawn in the plane of the wall from the boss through the centre of the wallsaid dimple lying on the opposite side of the centre at the same distance therefrom as the relevant boss whereby change of appearance or image is rendered possible by turning about the transverse axis, and that (2) the pattern of distribution is symmetrical in respect of the relevant central line so 'as to enable said change of appearance by turning about the centre line. Of course, only one of said conditions as regard the distribution need to be fulfilled in order to render a change of appearance or image possible by turning the wall. In this manner the walls indicated at 3 may be identical to the walls indicated at 2 but in the pack merely walls 3 are turned in relation to walls 2 in one or the other of the manners indicated above. In a. pack assembled by such identical walls each free space 6 as clearly shown 4 in FIG. 10 will be formed between equally turned walls while each jointed space 5 will be formed between unequally turned walls, and more particularly, the equally turned walls forming every second free space are unequally turned in relation to the equally turned Walls forming the remaining free spaces.

As an example of a type of plate heat exchangers of the type to which the invention relates we have selected a cross current apparatus with square walls because such an apparatus is most easy to illustrate clearly and is most simple to serve as the basis of a description of the invention. However, the application of the invention is not restricted to any determined type of plate heat exchanger. For example, the walls may be elongated and have contours of any shape and the apparatus may be constructed for counter current or parallel-flow. Only in the case where a pack of walls according to the invention is to consist of identical walls said contours should be such as to render it possible that also unequally turned walls as above may be assembled so as to cover one another entirely. The inlets and outlets for the heat exchanging media may consist of slots or gaps between the outer contours of the walls or of a series of apertures through the planes of the walls, etc.

What we claim is:

In a heat exchanger of the indirect plate type having a pack of heat transferring walls of thin plate material arranged in spaced face to face relation, the interspaces between the walls constituting passages for heat exchanging fluids, each such Wall at each side being formed with a large number of dimples therein, the material of each such wall encompassing said dimples forming corresponding bosses on the opposite side of the wall extending out from the plate material so that at each side of each wall such dimples and bosses are alternatively distributed over the wall surface, said walls being assembled in said pack with the dimples and bosses of opposed plates bordering each interspace being positioned in different relationship to each other in difierent interspaees and in every second such interspace the bosses of the one wall extending into the interspace being in spaced registering relationship with respect to the dimples formed in the other wall bordering said interspace and in the remaining such interspaces the bosses of one wall bordering the interspaces being in abutting registering relationship with respect to the bosses of the other wall bordering said interspace, a substantial number of said abutted bosses having the engaged tops thereof secured together in top to top relationship.

References Cited in the file of this patent UNITED STATES PATENTS 1,751,757 Phillips Mar. 25, 1930 1,775,103 Home Sept. 9, 1930 2,959,400 Simpelaar Nov. 8, 1960 

